Vegetative filter strips for reducing atrazine and sediment runoff transport

ABSTRACT:

A rainfall simulation study was performed on twelve vegetative filter strips (VFS), six 1.5 × 4.6 m (5 × 15 ft) long, and six 1.5 × 9.1 m (5 × 30 ft) long, to determine: (1) the effects of vegetative filter strips on atrazine and sediment transport in runoff inflow with an average of 7,650 mg L-¹ sediment (WS) and no-sediment (NS), and (2) the effects of vegetative filter strips length (4.6 and 9.1 m) (15 and 30 ft), and thus area ratio (with constant width), on atrazine and sediment transport. Herbicide runoff losses were simulated by adding a dilute atrazine solution as inflow (with sediment and without sediment) to the upper end of the vegetative filter strips. The with-sediment treatment was used to represent conventional tillage, while the without-sediment treatment represented no-tillage. Atrazine, and bromide (Br) as a hydrologic tracer, were dissolved in the inflow to the vegetative filter strips at a concentration of approximately 1 and 23 mg L-¹, respectively. The results showed that for the with-sediment inflow treatment, the 87% reduction in sediment transport for the 9.1 m (30 ft) vegetative filter strips was significantly (P = 0.05) greater than the 71% reduction for the 4.6 m (15 ft) vegetative filter strips. There was no significant difference in atrazine transport between the with-sediment and without-sediment treatments, but the 80% reduction in atrazine transport for the 9.1m (30 ft) vegetative filter strips was significantly greater than the 31% reduction for the 4.6 m (15 ft) vegetative filter strips. Infiltration of inflow was a dominant factor in reducing atrazine transport with vegetative filter strips, and the Br data showed that a higher proportion of inflow infiltrated than did rainfall.